Three-dimensional object forming liquid, three-dimensional object forming liquid set, three-dimensional object producing method, and three-dimensional object

ABSTRACT

Provided is a three-dimensional object producing method, including: a first step of forming a film by delivering a first liquid as a hydrogel precursor including at least a multifunctional monomer; and a second step of curing the film formed in the first step, wherein the first step and the second step are repeated a plurality of times.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a three-dimensional object formingliquid, a three-dimensional object forming liquid set, athree-dimensional object producing method, and a three-dimensionalobject.

Description of the Related Art

In recent years, there have been proposed inkjet stereolithographytechniques of forming a three-dimensional object by forming an image ata necessary portion of the object by an inkjet method using a liquidphoto-curable resin, and stacking up layers of such images. In theinkjet stereolithography techniques, there is proposed a method ofsimultaneously forming a support member made of a different materialfrom that of a three-dimensional object to prevent deformation or fallof the three-dimensional object during three-dimensional formationthereof (see, e.g., Japanese Patent (JP-B) Nos. 4366538 and 4908679).

Recently, there have been increasing needs for gel-state or softthree-dimensional objects having stereoscopic fine structures, such asmedical organ models and scaffoldings for cells used in regenerativemedicine. However, there have not yet been provided three-dimensionalobject producing methods that can reproduce complicated fine structuresfrom three-dimensional data. Particularly, organ models used for medicalprocedure trainings, etc. include complicated internal structures suchas vessel structures such as blood vessels inside the organs, and tumorportions, and it is very difficult to produce such organ models withmolds.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a three-dimensionalobject producing method that can produce complicated finethree-dimensional objects represented by organ models, etc. easily andefficiently.

A three-dimensional object producing method of the present invention asa means for solving the problem described above includes:

a first step of forming a film by delivering a first liquid as ahydrogel precursor including at least a multifunctional monomer; and

a second step of curing the film formed in the first step, wherein thefirst step and the second step are repeated a plurality of times.

The present invention can provide a three-dimensional object producingmethod that can produce complicated fine three-dimensional objectsrepresented by organ models, etc. easily and efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exemplary diagram illustrating an example of a layeredmineral

FIG. 1B is an exemplary diagram illustrating an example of a state ofthe layered mineral illustrated in FIG. 1A being dispersed in water.

FIG. 2 is a schematic diagram illustrating an example of athree-dimensional object forming apparatus used in a three-dimensionalobject producing method of the present invention.

FIG. 3 is a schematic diagram illustrating another example of athree-dimensional object forming apparatus used in a three-dimensionalobject producing method of the present invention.

FIG. 4A is a schematic perspective diagram illustrating an example of athree-dimensional object produced by a three-dimensional objectproducing method of the present invention.

FIG. 4B is a schematic cross-sectional diagram of FIG. 4A.

DETAILED DESCRIPTION OF THE INVENTION (Three-Dimensional Object FormingLiquid (First Liquid))

A three-dimensional object forming liquid of the present invention,i.e., a first liquid used in a three-dimensional object producing methodof the present invention includes a hydrogel precursor, and furtherincludes other components according to necessity.

<Hydrogel Precursor>

The hydrogel precursor includes at least a multifunctional monomer,preferably includes water, an organic solvent, a layered mineral, amonofunctional monomer, and a polymerization initiator, and furtherincludes other components according to necessity.

—Multifunctional Monomer—

The multifunctional monomer is a compound having two or more unsaturatedcarbon-carbon bonds, and preferably an active energy ray-curablemonomer. Examples thereof include bifunctional monomers, trifunctionalmonomers, and trifunctional or greater monomers.

It is preferable that a homopolymer of the multifunctional monomer bewater-soluble. In the present invention, the homopolymer of themultifunctional monomer is referred to as being water-soluble when, forexample, the homopolymer (1 g) is mixed in water (100 g) having atemperature of 30° C. and stirred, 90% by mass or greater of thehomopolymer dissolves.

Examples of the bifunctional monomers include tripropylene glycoldi(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethyleneglycol di(meth)acrylate, polypropylene glycol di(meth)acrylate,neopentyl glycol hydroxy pivalic acid ester di(meth)acrylate (MANDA),hydroxy pivalic acid neopentyl glycol ester di(meth)acrylate (HPNDA),1,3-butane diol di(meth)acrylate (BGDA), 1,4-butane dioldi(meth)acrylate (BUDA), 1,6-hexanediol di(meth)acrylate (HDDA),1,9-nonanediol di(meth)acrylate, diethylene glycol di(meth)acrylate(DEGDA), neopentyl glycol di(meth)acrylate (NPGDA), tripropylene glycoldi(meth)acrylate (TPGDA), caprolactone-modified hydroxy pivalic acidneopentyl glycol ester di(meth)acrylate, propoxylated neopentyl glycoldi(meth)acrylate, ethoxy-modified bisphenol A di(meth)acrylate,polyethylene glycol 200 di(meth)acrylate, polyethylene glycol 400di(meth)acrylate, and methylene bis acrylamide. One of these may be usedalone, or two or more of these may be used in combination.

Examples of the trifunctional monomers include trimethylol propanetri(meth)acrylate (TMPTA), pentaerythritol tri(meth)acrylate (PETA),triallyl isocyanate, tris(2-hydroxy ethyl)isocyanuratetri(meth)acrylate, ethoxylated trimethylol propane tri(meth)acrylate,propoxylated trimethylol propane tri(meth)acrylate, and propoxylatedglyceryl tri(meth)acrylate. One of these may be used alone, or two ormore of these may be used in combination.

Examples of the trifunctional or greater monomers includepentaerythritol tetra(meth)acrylate, ditrimethylol propanetetra(meth)acrylate, dipentaerythritol hydroxy penta(meth)acrylate,ethoxylated pentaerythritol tetra(meth)acrylate, penta(meth)acrylateester, and dipentaerythritol hexa(meth)acrylate (DPHA). One of these maybe used alone, or two or more of these may be used in combination.

A content of the multifunctional monomer is preferably from 0.001% bymass to 1% by mass, and more preferably from 0.01% by mass to 0.5% bymass relative to the whole amount of the three-dimensional objectforming liquid. When the content is in the range of from 0.001% by massto 1% by mass, elastic modulus and hardness of the hydrogel to beobtained can be adjusted to adequate ranges.

—Water—

The water may be, for example, pure water or ultrapure water such asion-exchanged water, ultrafiltrated water, reverse osmotic water, anddistilled water. Other components such as an organic solvent, etc. maybe dissolved or dispersed in the water according to such purposes as toimpart a moisture-retaining property, impart an antibacterial activity,impart conductivity, adjust hardness, etc.

The content of the water is not particularly limited, and may beappropriately selected according to the purpose.

—Organic Solvent—

The organic solvent is preferably water-based, and examples thereofinclude alcohols such as ethanol, ethers, and ketones.

The organic solvent is not particularly limited, and an appropriateorganic solvent may be selected according to the purpose. Examplesthereof include 1,2,6-hexane triol, 1,2-butanediol, 1,2-hexanediol,1,2-pentanediol, 1,3-dimethyl-2-imidazolidinone, 1,3-butanediol,1,3-propane diol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,2,2-dimethyl-1,3-propane diol, 2,3-butanediol, 2,4-pentanediol,2,5-hexanediol, 2-ethyl-1,3-hexanediol, 2-pyrrolidone,2-methyl-1,3-propane diol, 2-methyl-2,4-pentanediol,3-methyl-1,3-butanediol, 3-methyl-1,3-hexanediol,N-methyl-2-pyrrolidone, N-methyl pyrrolidinone, β-butoxy-N,N-dimethylpropion amide, β-methoxy-N,N-dimethyl propion amide, γ-butyrolactone,ε-caprolactam, ethylene glycol, ethylene glycol-n-butyl ether, ethyleneglycol-n-propyl ether, ethylene glycol phenyl ether, ethylene glycolmono-2-ethyl hexyl ether, ethylene glycol monoethyl ether, glycerin,diethylene glycol, diethylene glycol-n-hexyl ether, diethylene glycolmethyl ether, diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, diethylene glycol monomethyl ether, diglycerin,dipropylene glycol, dipropylene glycol-n-propyl ether, dipropyleneglycol monomethyl ether, dimethyl sulfoxide, sulfolane, thio diglycol,tetraethylene glycol, triethylene glycol, triethylene glycol ethylether, triethylene glycol dimethyl ether, triethylene glycol monobutylether, triethylene glycol methyl ether, tripropylene glycol,tripropylene glycol-n-propyl ether, tripropylene glycol methyl ether,trimethylol ethane, trimethylol propane, propyl propylene diglycol,propylene glycol(1,2-propane diol), propylene glycol-n-butyl ether,propylene glycol-t-butyl ether, propylene glycol phenyl ether, propyleneglycol monoethyl ether, hexylene glycol, polyethylene glycol, andpolypropylene glycol. One of these may be used alone, or two or more ofthese may be used in combination.

A content of the organic solvent is preferably from 1% by mass to 40% bymass, and more preferably from 5% by mass to 20% by mass relative to thewhole amount of the three-dimensional object forming liquid.

—Layered Mineral—

The layered mineral is preferably a layered mineral dispersed in waterin a state of single layers.

Here, the layered mineral is in a state that two-dimensional disk-shapedcrystals including unit cells in the crystals are layered, asillustrated in FIG. 1A. When dispersed in water, the layered mineralseparates into the state of individual single layers and becomesdisk-shaped crystals, as illustrated in FIG. 1B.

The layered mineral is not particularly limited, and an appropriatelayered mineral may be selected according to the purpose. Examplesthereof include water-swellable layered clay minerals.

Examples of the water-swellable layered clay minerals includewater-swellable smectite, and water-swellable mica. More specificexamples include water-swellable hectorite, water-swellablemontmorillonite, water-swellable saponite, and water-swellable syntheticmica that include sodium as interlayer ions.

The water swellability means a property that the layers of the layeredmineral become dispersed in water by the water molecules beingintercalated between the layers, as illustrated in FIG. 1B.

As the water-swellable layered clay mineral, one of those describedabove may be used alone, or two or more of those described above may beused in combination. The water-swellable layered clay mineral may be anappropriately synthesized product or may be a commercially availableproduct.

Examples of commercially available products include a synthetichectorite (LAPONITE XLG manufactured by Rock Wood Co., Ltd.), SWN(manufactured by Coop Chemical Ltd.), and a fluorinated hectorite SWF(manufactured by Coop Chemical Ltd.). Among these, the synthetichectorite is preferable.

A content of the layered mineral is preferably from 1% by mass to 40% bymass, and more preferably from 1% by mass to 15% by mass relative to thewhole amount of the three-dimensional object forming liquid. When thecontent is in the range of from 1% by mass to 40% by mass, the viscosityof the three-dimensional object forming liquid will be adequate, andjettability thereof by inkjet and the hardness of a three-dimensionalobject will be favorable.

—Monofunctional Monomer—

The monofunctional monomer is a compound having one unsaturatedcarbon-carbon bond. Examples thereof include acrylamide, N-substitutedacrylamide derivatives, N,N-disubstituted acrylamide derivatives,N-substituted methacrylamide derivatives, N, N-disubstitutedmethacrylamide derivatives, and other monofunctional monomers. One ofthese may be used alone, or two or more of these may be used incombination.

The N-substituted acrylamide derivatives, the N,N-disubstitutedacrylamide derivatives, the N-substituted methacrylamide derivatives, orthe N,N-disubstituted methacrylamide derivatives are not particularlylimited, and an appropriate example may be selected according to thepurpose. Examples thereof include N,N-dimethyl acrylamide, andN-isopropyl acrylamide.

Examples of the other monofunctional monomers include 2-ethyl hexyl(meth)acrylate (EHA), 2-hydroxy ethyl (meth)acrylate (HEA), 2-hydroxypropyl (meth)acrylate (HPA), caprolactone-modified tetrahydro furfuryl(meth)acrylate, isobornyl (meth)acrylate, 3-methoxy butyl(meth)acrylate,tetrahydro furfuryl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate,tridecyl (meth)acrylate, caprolactone (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, and urethane (meth)acrylate. One of these may beused alone, or two or more of these may be used in combination.

When the monofunctional monomer is polymerized, a water-soluble organicpolymer having an amide group, an amino group, a hydroxyl group, atetramethyl ammonium group, a silanol group, an epoxy group, or the likeis obtained.

A water-soluble organic polymer having an amide group, an amino group, ahydroxyl group, a tetramethyl ammonium group, a silanol group, an epoxygroup, or the like is an advantageous constituent component formaintaining the strength of the hydrogel.

A content of the monofunctional monomer is not particularly limited, andmay be appropriately selected according to the purpose. However, it ispreferably from 1% by mass to 10% by mass, and more preferably from 1%by mass to 5% by mass relative to the whole amount of thethree-dimensional object forming liquid. When the content is in therange of from 1% by mass to 10% by mass, there are advantages thatdispersion stability of the layered mineral in the three-dimensionalobject forming liquid is maintained, and that stretchability of athree-dimensional object is improved. The stretchability means aproperty that a three-dimensional object does not tear when stretched.

—Polymerization Initiator—

Examples of the polymerization initiator include a thermalpolymerization initiator, and a photopolymerization initiator.

—Thermal Polymerization Initiator—

The thermal polymerization initiator is not particularly limited, and anappropriate thermal polymerization initiator may be selected accordingto the purpose. Examples thereof include azo-initiators, peroxideinitiators, persulfate initiators, and redox (oxidoreduction)initiators.

Examples of the azo-initiators include2,2′-azobis(4-methoxy-2,4-dimethyl valeronitrile) (VAZO 33),2,2′-azobis(2-amidino propane) dihydrochloride (VAZO 55),2,2′-azobis(2,4-dimethyl valeronitrile) (VAZO 52),2,2′-azobis(isobutyronitrile) (VAZO 64), 2,2′-azobis-2-methylbutyronitrile (VAZO 67), and 1,1-azobis(1-cyclohexane carbonitrile)(VAZO 88) (all available from DuPont Chemical Company), VA-044, VA-46B,V-50, VA-057, VA-061, VA-067, VA-086, 2,2′-azobis(2-cyclopropylpropionitrile), and 2,2′-azobis(methyl isobutyrate) (V-601) (allavailable from Wako Pure Chemical Industries, Ltd.).

Examples of the peroxide initiators include benzoyl peroxide, acetylperoxide, lauroyl peroxide, decanoyl peroxide, dicetyl peroxydicarbonate, di(4-t-butyl cyclohexyl)peroxy dicarbonate (PERKADOX 16S)(available from Akzo Nobel Inc.), di(2-ethyl hexyl)peroxy dicarbonate,t-butyl peroxy pivalate (LUPERSOL 11) (available from Elf Atochem Inc.),t-butyl peroxy-2-ethyl hexanote (TRIGONOX 21-C50) (available from AkzoNobel Inc.), and dicumyl peroxide.

Examples of the persulfate initiators include potassium persulfate,sodium persulfate, and ammonium persulfate.

Examples of the redox (oxidoreduction) initiators include combinationsof reductants such as sodium hydrogen meta sulfite and sodium hydrogensulfite with the persulfate initiators, systems based on the organicperoxides and tertiary amines (e.g., a system based on benzoyl peroxideand dimethyl aniline), and systems based on organic hydro peroxides andtransition metals (e.g., a system based on cumene hydro peroxide andcobalt naphthenate).

—Photopolymerization Initiator—

The photopolymerization initiator may be an arbitrary substance thatproduces radicals when irradiated with light (particularly, ultravioletrays having a wavelength of from 220 nm to 400 nm).

Examples of the photopolymerization initiator include acetophenone,2,2-diethoxy acetophenone, p-dimethyl amino acetophenone, benzophenone,2-chlorobenzophenone, p,p′-dichlorobenzophenone, p,p-bis diethyl aminobenzophenone, Michler ketone, benzyl, benzoin, benzoin methyl ether,benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether,benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal,thioxanthone, 2-chlorothioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-one,1-(4-isopropyl phenyl)2-hyroxy-2-methyl propan-1-one, methyl benzoylformate, 1-hydroxy cyclohexyl phenyl ketone, azobis isobutylonitrile,benzoyl peroxide, and di-tert-butyl peroxide. One of these may be usedalone, or two or more of these may be used alone.

A content of the polymerization initiator is not particularly limited,and may be appropriately selected according to the purpose. However, itis preferably from 0.01% by mass to 3% by mass relative to the wholemonomer amount in the three-dimensional object forming liquid.

—Other Components—

The other components are not particularly limited, and appropriatecomponents may be selected according to the purpose. Examples thereofinclude surfactants, colorants, stabilizing agents, water-solubleresins, low-boiling-point alcohols, surface treating agents, viscositymodifiers, tackifiers, antioxidants, anti-aging agents, cross-linkingpromoters, ultraviolet absorbers, plasticizers, antiseptics, anddispersants.

—Physical Properties of Three-Dimensional Object Forming Liquid—

A surface tension of the three-dimensional object forming liquid is notparticularly limited, and may be appropriately selected according to thepurpose. However, it is preferably from 20 mN/m to 45 mN/m, and morepreferably from 25 mN/m to 34 mN/m.

When the surface tension is 20 mN/m or greater, jettability of thethree-dimensional object forming liquid during three-dimensional objectformation will be good. When the surface tension is 45 mN/m or less, afilling property of the three-dimensional object forming liquid whenfilled into jet nozzles, etc. will be good.

The surface tension can be measured with, for example, a surfacetensiometer (an automatic contact angle gauge DM-701 manufactured byKyowa Interface Science Co., Ltd.).

A viscosity of the three-dimensional object forming liquid is notparticularly limited, and may be appropriately selected according to thepurpose. However, it is preferably from 3 mPa·s to 20 mPa·s, and morepreferably from 6 mPa·s to 12 mPa·s at 25° C.

When the viscosity is in the range of from 3 mPa·s to 20 mPa·s,jettability of the three-dimensional object forming liquid duringthree-dimensional object formation will be good.

The viscosity can be measured with, for example, a rotary viscometer(VISCOMATE VM-150III manufactured by Toki Sangyo Co., Ltd.) at 25° C.

An 80% strain compressive stress of a hydrogel that is obtained bycuring the three-dimensional object forming liquid is preferably 0.4 MPaor greater. When the 80% strain compressive stress is 0.4 MPa orgreater, there is an advantage that a hardness close to a living bodytexture can be reproduced, and a realistic organ model can be provided.

The 80% strain compressive stress can be measured with, for example, auniversal tester (AG-I manufactured by Shimadzu Corporation).

The three-dimensional object forming liquid of the present invention canbe used favorably for production of various three-dimensional objects,and can be used particularly favorably for a three-dimensional objectforming liquid set of the present invention, a three-dimensional objectproducing method of the present invention, and a three-dimensionalobject of the present invention.

(Three-Dimensional Object Forming Liquid Set)

A three-dimensional object forming liquid set of the present inventionincludes a first liquid and a second liquid, preferably includes a thirdliquid and a fourth liquid, and further includes other components, etc.according to necessity.

<Second Liquid>

The second liquid includes a hydrogel precursor, and may be similar tothe first liquid except that it is compositionally different from thefirst liquid.

Being compositionally different from the first liquid means that atleast any of the kinds and the contents of the components constitutingthe second liquid is different from the first liquid.

It is preferable that the first liquid and the second liquid be cured tohydrogels that are different from each other in elastic modulus (80%strain compressive stress or compressive elastic modulus). This makes itpossible to efficiently produce a three-dimensional object that includesin the single three-dimensional object, regions different in elasticmodulus.

<Third Liquid>

The third liquid includes at least a polymerization initiator,preferably includes water and an organic solvent, and may furtherincludes a multifunctional monomer, a monofunctional monomer, and othercomponents according to necessity. Note that the third liquid is free ofa layered mineral.

—Polymerization Initiator—

Examples of the polymerization initiator includes a thermalpolymerization initiator and a photopolymerization initiator. Of these,a photopolymerization initiator is preferable in terms of storagestability.

The thermal polymerization initiator and the photopolymerizationinitiator may be the same as those presented above for thethree-dimensional object forming liquid of the present invention.

Independent use of the photopolymerization initiator in the third liquidthat is different from at least any one of the first liquid and thesecond liquid makes it possible to secure storage stability duringstorage of at least any one of the first liquid and the second liquid,and also to add the photopolymerization initiator in a greater amountthan when it is assumed that the photopolymerization initiator is usedin at least any one of the first liquid and the second liquid for thesame sake of storage stability. This increases the rate ofpolymerization of a three-dimensional object, and enables efficientproduction thereof.

In terms of storage stability, it is preferable that the content of thephotopolymerization initiator in the third liquid be greater than thatin at least any one of the first liquid and the second liquid. It ismore preferable that at least any one of the first liquid and the secondliquid be free of a photopolymerization initiator.

The multifunctional monomer, the monofunctional monomer, and the othercomponents may be the same as those of the first liquid. It is possibleto appropriately select a more preferable monomer depending on thecombination with the polymerization initiator.

—Viscosity Change Rate—

A viscosity change rate of the third liquid before and after it is leftat 50° C. for two weeks is preferably 20% or less, and more preferably10% or less.

When the viscosity change rate is 10% or less, the storage stability ofthe third liquid is adequate, and jetting stability of the third liquidwhen it is delivered by an inkjet method will be good.

The viscosity change rate before and after being left at 50° C. for twoweeks can be measured as follows.

The third liquid is put in a polypropylene-made wide-mouthed bottle (50mL), and left in a constant-temperature bath of 50° C. for two weeks.After this, the bottle is taken out from the constant-temperature bath,left until it becomes room temperature (25° C.), and the viscosity ofthe third liquid is measured. The viscosity change rate is calculatedaccording to the formula below, where the viscosity of the third liquidbefore put in the constant-temperature bath is referred to aspre-storage viscosity, and the viscosity of the third liquid after takenout from the constant-temperature bath is referred to as post-storageviscosity. The pre-storage viscosity and the post-storage viscosity canbe measured with TYPE R VISCOMETER (manufactured by Toki Sangyo Co.,Ltd.) at 25° C.

Viscosity change rate (%)=[(post-storage viscosity)−(pre-storageviscosity)]/(pre-storage viscosity)×100

The pre-storage viscosity of the third liquid is preferably 20 mPa·s orless, more preferably from 3 mPa·s to 20 mPa·s, and yet more preferablyfrom 3 mPa·s to 12 mPa·s at 25° C. When the viscosity is 20 mPa·s orless, jetting from inkjet nozzles will be stable.

The post-storage viscosity of the third liquid is preferably from 3mPa·s to 12 mPa·s at 25° C.

<Fourth Liquid>

The fourth liquid is a liquid that is to become a hard formed body forsupporting a three-dimensional object made of a hydrogel (a soft body)(the fourth liquid will also be referred to as “hard formed bodymaterial”). The fourth liquid includes a curable material, preferablyincludes a polymerization initiator, further includes other componentsaccording to necessity, but is free of water and a layered mineral.

—Curable Material—

The curable material is preferably a compound that inducespolymerization reaction and cures upon irradiation of active energy rays(ultraviolet rays, electron beams, etc.), heating, etc. An appropriatecurable material may be selected according to the purpose, and examplesthereof include active energy ray-curable compounds, and thermosettingcompounds. Among these, materials that are liquid at normal temperatureare preferable.

The active energy ray-curable compounds are monomers having aradically-polymerizable unsaturated double bond in a molecular structurethereof and having a relatively low viscosity, and an appropriate activeenergy ray-curable compound may be used as selected from themultifunctional monomers and monofunctional monomers used in the firstliquid and the second liquid. One of these may be used alone, or two ormore of these may be used in combination.

The content of the curable material is not particularly limited, and maybe appropriately selected according to the purpose.

—Other Components—

The other components are not particularly limited, and appropriatecomponents may be selected according to the purpose. Examples thereofinclude colorants, water-soluble resins, low-boiling-point alcohols,surfactants, viscosity modifiers, tackifiers, antioxidants, anti-agingagents, cross-linking promoters, ultraviolet absorbers, plasticizers,antiseptics, and dispersants.

The surface tension of the fourth liquid is not particularly limited,and may be appropriately selected according to the purpose. However, itis preferably from 20 mN/m to 45 mN/m, and more preferably from 25 mN/mto 34 mN/m.

When the surface tension is 20 mN/m or greater, jettability duringthree-dimensional object formation will be good. When the surfacetension is 45 mN/m or less, a filling property of the fourth liquid whenfilled into jetting nozzles for three-dimensional object formation willbe good.

The surface tension can be measured with, for example, a surfacetensiometer (an automatic contact angle gauge DM-701 manufactured byKyowa Interface Science Co., Ltd.).

The viscosity of the fourth liquid is not particularly limited, may beappropriately selected according to the purpose, and can beappropriately adjusted based on temperature adjustment. However, it ispreferably from 3 mPa·s to 20 mPa·s, and more preferably from 6 mPa·s to12 mPa·s at 25° C.

In the viscosity range of from 3 mPa·s to 20 mPa·s, jettability of thefourth liquid during three-dimensional object formation will be good.

The viscosity can be measured with, for example a rotary viscometer(VISCOMATE VM-150III manufactured by Sangyo Co., Ltd.) at 25° C.

The three-dimensional object forming liquid set of the present inventioncan be used favorably for production of various three-dimensionalobjects, can be used favorably for production of a complicated finethree-dimensional object including in the single three-dimensionalobject, regions different in elastic modulus, represented by an organmodel, etc., and can be used particularly favorably for athree-dimensional object producing method of the present invention and athree-dimensional object of the present invention, which are to bedescribed below.

(Three-Dimensional Object Producing Method) <First Mode>

A three-dimensional object producing method according to a first mode ofthe present invention includes a first step and a second step,preferably includes a fifth step and an eighth step, and furtherincludes other steps according to necessity.

—First Step—

The first step is a step of forming a film by delivering a first liquidas a hydrogel precursor including at least a multifunctional monomer.

The first liquid may be the same as the three-dimensional object formingliquid of the present invention.

A method for delivering the first liquid is not particularly limited,and an appropriate method may be selected according to the purpose aslong as the method can apply liquid droplets made of the first liquid toan intended position with an appropriate precision. Examples thereofinclude a dispenser method, a spray method, and an inkjet method. Knownapparatuses can be used favorably for carrying out these methods.

Among these, the inkjet method is particularly preferable in the presentinvention. The inkjet method is advantageous over the spray method inbetter liquid droplet quntitativity, advantageous over the dispensermethod in broader coating area, and is preferable because it is capableof forming a complicated three-dimensional shape precisely andefficiently.

—Second Step—

The second step is a step of curing the film formed in the first step.

Examples of a unit configured to cure the film include ultraviolet(UV)-emitting lamps, electron beam-emitting devices, and heatingdevices. It is preferable that the unit configured to cure the filminclude an ozone removal system.

The kinds of the ultraviolet (UV)-emitting lamps include high-pressuremercury lamps, ultrahigh pressure mercury lamps, and metal halides.

Although the ultrahigh pressure mercury lamps are point light sources,Deep UV mercury lamps combined with an optical system and enhanced inlight use efficiency can emit a short-wavelength range.

The metal halides are effective for colored materials because they havea broad wavelength range, and use halides of metals such as Pb, Sn, Fe,etc., from which an appropriate one can be selected according to theabsorption spectrum of the photopolymerization initiator. For example,commercially available products such as H LAMP, D LAMP, and V LAMPmanufactured by Fusion System may be used.

Heating methods by the heating devices include a method of heating aformed film by bringing it into contact with a heat source, and a methodof heating a formed film without bringing it into contact with a heatsource, such as a method of irradiating a formed with far infrared rays,near infrared rays, microwaves, or the like, and a method of blowing aformed film with hot air.

The heating may be performed alone, but may also be performed beforeultraviolet irradiation, simultaneously with ultraviolet irradiation, orafter ultraviolet irradiation.

The cured film is in the form of including water and componentsdissolved in water in a three-dimensional network structure formed by awater-soluble organic polymer produced from polymerization of themonofunctional monomer and the multifunctional monomer being combinedwith the layered mineral.

—Fifth Step—

The fifth step is a step of delivering a third liquid including at leasta polymerization initiator to the same position as where the firstliquid is delivered.

It is preferable that the fifth step be performed between the first stepand the second step.

The third liquid includes a polymerization initiator, and may be similarto the first liquid except that it is compositionally different from thefirst liquid. Being compositionally different from the first liquidmeans that at least any of the kinds and the contents of the componentsconstituting the first liquid is different from the third liquid.

Delivering the third liquid to the same position as where the firstliquid is delivered means delivering the third liquid over the firstliquid delivered previously in an overlapping manner. The third liquidis compatible with the first liquid. Therefore, by delivering the thirdliquid to the same position as where the first liquid is delivered, itis possible to make the polymerization initiator included in the thirdliquid serve as a polymerization initiator for the monomers included inthe first liquid.

The third liquid may be the same as the third liquid included in thethree-dimensional object forming liquid set of the present invention.

A method for delivering the third liquid is not particularly limited,and an appropriate method may be selected according to the purpose aslong as it is a method capable of applying liquid droplets made of thethird liquid to an intended position with an appropriate precision.Examples thereof include a dispenser method, a spray method, and aninkjet method.

—Eighth Step—

The eighth step is a step of forming a film by delivering a fourthliquid that is to become a hard formed body for supporting athree-dimensional object made of the hydrogel to a different positionfrom where the first liquid is delivered.

The fourth liquid may be the same as the fourth liquid included in thethree-dimensional object forming liquid set of the present invention.

Delivering the fourth liquid to a different position from where thefirst liquid is delivered means that the positions to where the fourthliquid and the first liquid are delivered do not overlap each other.Hence, the fourth liquid and the first liquid may adjoin each other. Thefourth liquid is compositionally different from the first liquid, andnot easily miscible with the first liquid. Therefore, even when thefourth liquid and the first liquid adjoin each other, the boundarybetween them after cured will be clear.

A method for delivering the fourth liquid is not particularly limited,and an appropriate method may be selected according to the purpose aslong as it is a method capable of applying liquid droplets made of thefourth liquid to an intended position with an appropriate precision.Examples thereof include a dispenser method, a spray method, and aninkjet method.

—Other Steps—

The other steps are not particularly limited, and appropriate steps maybe selected according to the purpose. Examples thereof include a dataprocessing step of acquiring and processing three-dimensional data, adetaching step of detaching a hydrogel from its support member (a hardformed body), a washing step of washing a three-dimensional object, anda polishing step of polishing a three-dimensional object.

The three-dimensional object producing method according to the firstmode repeats the respective steps a plurality of times. The number oftimes of repetition cannot be determined flatly because it variesdepending on the size, shape, structure, etc. of a three-dimensionalobject to be produced. As long as the thickness per layer is in therange of from 10 μm to 50 μm, an object can be formed with a goodprecision and without detachment. Hence, it is necessary to stack layersrepeatedly up until the height of the three-dimensional object to beproduced.

<Second Mode>

A three-dimensional object producing method according to a second modeof the present invention includes a first step, a third step, and afourth step, preferably includes a sixth step and a seventh step, andfurther includes other steps according to necessity.

—Third Step—

The third step is a step of forming a film by delivering a second liquidincluding a hydrogel precursor and compositionally different from thefirst liquid to a different position from where the first liquid isdelivered.

Delivering the second liquid to a different position from where thefirst liquid is delivered means that the positions to where the firstliquid and the second liquid are delivered do not overlap each other.Hence, the first liquid and the second liquid may adjoin each other. Thesecond liquid is compositionally different from the first liquid butcompatible with the first liquid. Therefore, the second liquid and thefirst liquid become compatibilized with each other at an adjoiningregion where they adjoin each other, and when cured, can form onehydrogel in which they are different in elastic modulus.

The first liquid and the second liquid may be the same as the firstliquid and the second liquid included in the three-dimensional objectforming liquid set of the present invention.

A method for delivering the second liquid is not particularly limited,and an appropriate method may be selected according to the purpose aslong as it is a method capable of applying liquid droplets made of thesecond liquid to an intended position with an appropriate precision.Examples thereof include a dispenser method, a spray method, and aninkjet method.

—Fourth Step —

The fourth step is a step of curing the films formed in the first stepand the third step respectively.

The film formed in the first step and the film formed in the third stepmay be cured simultaneously or separately. However, simultaneous curingis preferable in terms of productivity.

A unit configured to cure the films is not particularly limited, and anappropriate unit may be selected according to the purpose. For example,it may be the same as that in the second step of the three-dimensionalobject producing method according to the first mode.

—Sixth Step—

The sixth step is a step of delivering a third liquid including at leasta polymerization initiator to the same position as at least any one ofwhere the first liquid is delivered and where the second liquid isdelivered.

It is preferable that the sixth step be performed between the first stepand the third step, or between the third step and the fourth step.

The third liquid includes a polymerization initiator, and may be similarto the first liquid and the second liquid except that it iscompositionally different from the first liquid and the second liquid.Being compositionally different from the first liquid and the secondliquid means that at least any of the kinds and the contents of thecomponents constituting the first liquid and the second liquid isdifferent from the third liquid.

Delivering the third liquid to the same position as at least any one ofwhere the first liquid is delivered and where the second liquid isdelivered means delivering the third liquid over at least any one of thefirst liquid and the second liquid delivered previously in anoverlapping manner. The third liquid is compatible with the first liquidand the second liquid. Therefore, by delivering the third liquid to thesame position as at least any one of where the first liquid is deliveredand where the second liquid is delivered, it is possible to make thepolymerization initiator included in the third liquid serve as apolymerization initiator for the monomers included in the first liquidand the second liquid.

The third liquid may be the same as the third liquid included in thethree-dimensional object forming liquid set of the present invention.

A method for delivering the third liquid is not particularly limited,and an appropriate method may be selected according to the purpose aslong as it is a method capable of applying liquid droplets made of thethird liquid to an intended position with an appropriate precision.Examples thereof include a dispenser method, a spray method, and aninkjet method.

—Seventh Step—

The seventh step is a step of forming a film by delivering a fourthliquid that is to become a hard formed body for supporting athree-dimensional object made of the hydrogel to a different positionfrom at least any one of where the first liquid is delivered and wherethe second liquid is delivered.

The fourth liquid may be the same as the fourth liquid included in thethree-dimensional object forming liquid set of the present invention.

Delivering the fourth liquid to a different position from at least anyone of where the first liquid is delivered and where the second liquidis delivered means that the positions to where the fourth liquid, andthe first liquid and the second liquid are delivered do not overlap witheach other. Hence, the fourth liquid, and the first liquid and thesecond liquid may adjoin each other. The fourth liquid iscompositionally different from the first liquid and the second liquidand not easily miscible with them. Therefore, even when the fourthliquid and the first liquid or the second liquid adjoin each other, theboundary between them after cured will be clear.

A method for delivering the fourth liquid is not particularly limited,and an appropriate method may be selected according to the purpose aslong as it is a method capable of applying liquid droplets made of thefourth liquid to an intended position with an appropriate precision.Examples thereof include a dispenser method, a spray method, and aninkjet method.

—Other Steps—

The other steps are not particularly limited, and appropriate steps maybe selected according to the purpose. Examples thereof include a dataprocessing step of acquiring and processing three-dimensional data, adetaching step of detaching a hydrogel from its support member (a hardformed body), a washing step of washing a three-dimensional object, anda polishing step of polishing a three-dimensional object.

The three-dimensional object producing method according to the secondmode repeats the respective steps a plurality of times. The number oftimes of repetition cannot be determined flatly because it variesdepending on the size, shape, structure, etc. of a three-dimensionalobject to be produced. As long as the thickness per layer is in therange of from 10 μm to 50 μm, an object can be formed with a goodprecision and without detachment. Hence, it is necessary to stack layersrepeatedly up until the height of the three-dimensional object to beproduced.

The data processing step may be performed with reference to thedescription in JP-B No. 5239037. In the present invention, the processfrom data acquisition until jetting of the respective liquids using thethree-dimensional object forming liquid set is performed as below.

First, surface data or solid data of a three-dimensional shape designedwith a three-dimensional CAD or a three-dimensional shape acquired witha three-dimensional scanner or a digitizer is converted to an STLformat, and various data obtained as a result are input to athree-dimensional object forming apparatus. Based on the various datathat are input, the three-dimensional object forming apparatusdetermines a forming direction of a three-dimensional shape to beformed. The forming direction is not particularly limited, and it istypically preferable to select a direction in which the shortestdimension of the three-dimensional object is aligned in a Z-direction(i.e., a height direction).

After determining the forming direction, the three-dimensional objectforming apparatus calculates projected areas of the three-dimensionalshape on an X-Y plane, an X-Z plane, and a Y-Z plane. In order toreinforce the obtained block shape, the three-dimensional object formingapparatus moves each surface thereof except the top surface in the X-Yplane outward by an appropriate amount. The amount of move is notparticularly limited and varies depending on shape, size, and materialsused, but is from about 1 mm to 10 mm. In this way, thethree-dimensional object forming apparatus specifies a block shape thatencloses therein the shape to be formed (but is opened at the topsurface).

The three-dimensional object forming apparatus cuts (slices) the blockshape into round slices at one-layer-thickness intervals in theZ-direction. The thickness of one layer varies depending on thematerials used and cannot be determined flatly, but is preferably from10 μm to 50 μm. When there is one three-dimensional object to be formed,the block shape is positioned in the center of a Z-stage (i.e., a tableover which an object being formed is mounted, and is configured to liftdown each time one layer is formed by an amount corresponding to onelayer). When a plurality of three-dimensional objects are to be formedsimultaneously, the block shapes are positioned over the Z-stage, butmay also be stacked one upon another. The three-dimensional objectforming apparatus may perform such block shaping, slice data (contourdata) generation, and Z-stage positioning automatically upon designationof the materials used.

Next, based on the outermost contour line among the slice data, thethree-dimensional object forming apparatus controls the position fromwhich to jet each liquid by an inkjet method by performing in/outdetermination (i.e., determination of whether or not to jet each liquidof the three-dimensional object forming liquid set to a position on thecontour line).

The order of jetting each liquid of the three-dimensional object formingliquid set in the case where, for example, the first liquid, the secondliquid, and the fourth liquid are used is preferably the fourth liquidfor forming a support member first, and then at least any one of thefirst liquid and the second liquid for forming a three-dimensionalobject (a hydrogel) next. In such a jetting order, a pooling portionsuch as a groove, a dam, etc. is formed by the support member first, andat least any one of the first liquid and the second liquid is to bejetted into the pooling portion. This eliminates the risk of“dripping-off” of materials that are liquid at normal temperature andused as the first liquid and the second liquid, which allows use of awide variety of photo-curable resins, thermosetting resins, etc. Whenthe third liquid is also used, the jetting order is the same, exceptthat after at least any one of the first liquid and the second liquid isjetted, the third liquid is jetted to the same position as at least anyone of the position to which the first liquid is jetted and the positionto which the second liquid is jetted.

In order to shorten the time taken for the formation, preferable is amethod of jetting at least any one of the first liquid, the secondliquid, and the fourth liquid on each of the outward path and homewardpath of an integrated inkjet head and stacking layers thereby.Furthermore, by providing an active energy ray-emitting device (e.g., anultraviolet ray-emitting device) or an infrared ray-emitting device inthe proximity of the inkjet head, it is possible to save the time takenfor a smoothing process, and realize a high-speed object formation.

As described above, in the three-dimensional object producing method ofthe present invention, the liquids are jetted from minute pores by aninkjet method, a dispenser method, etc., which realizes a clearseparation and an immiscible incompatible state at where at least anyone of the first liquid and the second liquid applied in a mannercapable of forming an image on a layer-by-layer basis and yet to becured contacts the fourth liquid.

In a conventional object forming method, at least any one of the firstliquid and the second liquid, and the fourth liquid becomecompatibilized with each other at where they contact, and make theirboundary when photo-cured unclear. As a result, minute irregularityremains in the surface of the three-dimensional object. However, in thethree-dimensional object producing method of the present invention, atleast any one of the first liquid and the second liquid, and the fourthliquid remain incompatible with each other at where they contact, andmake their boundary after photo-cured clear. Furthermore, difference inhardness between the obtained three-dimensional object and the supportmember improves the detachability. This provides a better smoothnessover the surface of the three-dimensional object, and makes it possibleto skip or greatly reduce a polishing step after the object formation.

<Three-Dimensional Object Forming Apparatus>

FIG. 2 is a schematic diagram illustrating one example of athree-dimensional object forming apparatus used in the presentinvention.

The three-dimensional object forming apparatus of FIG. 2 uses a headunit in which inkjet heads are arranged, and is configured to jet atleast any one of the first liquid and the second liquid from anobject-jetting head unit 30, and the third liquid from supportmember-jetting head units 31 and 32, cure each liquid of thethree-dimensional object forming liquid set with adjoining ultravioletray-emitting devices or infrared ray-emitting devices 33 and 34, andstack layers thereby.

In FIG. 2, there is only one object-jetting head unit 30. However, twoor more of the object-jetting head unit 30 may be provided. Further, itis possible to additionally provide infrared ray-emitting devices(unillustrated) at the positions adjoining the ultraviolet ray-emittingdevices 33 and 34, and stack layers while heating and curing each liquidof the three-dimensional object forming liquid set.

A three-dimensional object 35 is produced in a manner that the fourthliquid is jetted from the support member-jetting head units 31 and 32and solidified to form a first support member layer including a poolingportion, at least any one of the first liquid and the second liquid isjetted into the pooling portion of the first support member layer fromthe object-jetting head unit 30, active energy rays are emitted toirradiate at least any one of the first liquid and the second liquid andform a first object layer, the fourth liquid is jetted over the firstsupport member layer and solidified to stack a second support memberlayer including a pooling portion, at least any one of the first liquidand the second liquid is jetted into the pooling portion of the secondsupport member layer, and active energy rays are emitted to irradiate atleast any one of the first liquid and the second liquid and stack asecond object layer over the first object layer.

When the multi-head unit moves in the direction of the arrow A, thesupport member-jetting head unit 31, the object-jetting head unit 30,and the ultraviolet ray-emitting device or infrared ray-emitting device34 are basically used to form a support member 36 and thethree-dimensional object 35 over an object support substrate 37. Notethat the support member-jetting head unit 32 and the ultravioletray-emitting device or infrared ray-emitting device 33 may be usedsupplementarily.

When the multi-head unit moves in the direction of the arrow B, thesupport member-jetting head unit 32, the object-jetting head unit 30,and the ultraviolet ray-emitting device or infrared ray-emitting device33 are basically used to form the support member 36 and thethree-dimensional object 35 over the object support substrate 37. Notethat the support member-jetting head unit 31 and the ultravioletray-emitting device or infrared ray-emitting device 34 may be usedsupplementarily.

Layers are stacked while a stage 38 is lifted down according to thenumber of layers stacked, in order for the object-jetting head unit 30,the support member-jetting head units 31 and 32, and the ultravioletray-emitting devices or infrared ray-emitting devices 33 and 34 to bemaintained at a constant gap from the three-dimensional object 35 andthe support member 36.

FIG. 3 is a schematic diagram illustrating another example of objectproducing steps that can provide a better smoothness to each layer thanby the object producing steps of FIG. 2. Basic steps are identical withFIG. 2, but the difference is that the ultraviolet ray-emitting devicesor infrared ray-emitting devices 33 and 34 are arranged between theobject-jetting head unit 30, and the support member-jetting head units31 and 32.

Further, in the three-dimensional object forming apparatus 39, theultraviolet ray-emitting devices or infrared ray-emitting devices 33 and34 are used in both moving directions of the arrows A and B, and thesurface of at least any one of the first liquid and the second liquidthat is/are stacked is smoothed by the heat generated along with theirultraviolet irradiation or infrared irradiation, which improvesdimensional stability of the three-dimensional object.

The three-dimensional object forming apparatus 39 may be provided withan ink collecting system, a recycling system, etc. It may also beprovided with blades for removing each liquid of the three-dimensionalobject forming liquid set that has adhered to a nozzle surface, and adetecting system for detecting nozzles that do not jet. Furthermore, itis also preferable that the ambient temperature inside the apparatusduring formation be controlled.

(Three-Dimensional Object)

A three-dimensional object of the present invention is made of ahydrogel produced by curing the three-dimensional object forming liquidof the present invention, and preferably includes at least a firstregion made of a first hydrogel and a second region made of a secondhydrogel different from the first hydrogen in elastic modulus (80%strain compressive stress or compressive elastic modulus). Althoughdepending on the purpose of use, it is preferable that the 80% straincompressive stress of any one of the first hydrogel and the secondhydrogel be 0.4 MPa or greater, or that the compressive elastic modulusthereof be 0.3 MPa or greater. Hence, there is obtained athree-dimensional object (hydrogel) that includes in the singlethree-dimensional object, regions different in elastic modulus.

The 80% strain compressive stress can be measured with, for example, auniversal tester (AG-I manufactured by Shimadzu Corporation). Thecompressive elastic modulus can be obtained by calculating a differencebetween a 10% strain compressive stress and a 20% strain compressivestress, as a slope at a displacement of 10%.

It is preferable that a hydrogel produced from the hydrogel precursor bea hydrogel including water in a three-dimensional network structureformed by a water-soluble organic polymer produced from polymerizationof at least a multifunctional monomer being combined with dispersedsingle layers of a layered mineral.

Examples of the water-soluble organic polymer include organic polymershaving an amide group, an amino group, a hydroxyl group, a tetramethylammonium group, a silanol group, an epoxy group, etc.

The water-soluble organic polymer is a constituent componentadvantageous for maintaining the strength of a water-based gel.

The organic polymer may be a homopolymer or a heteropolymer (acopolymer), may be modified, may have a known functional groupincorporated, or may be in the form of a salt, but is preferably ahomopolymer.

In the present invention, “water-soluble” of the water-soluble polymermeans a property that, for example, when the water-soluble polymer (1 g)is mixed in water (100 g) having a temperature of 30° C. and stirred,90% by mass or greater thereof dissolves.

As illustrated in FIG. 4A and FIG. 4B, in the three-dimensional objectof the present invention, it is preferable that the first region (aregion A) enclose the second region (a region B) therein completely.

The three-dimensional object is used favorably as an organ model, etc.,because it can include in the single three-dimensional object, regionsdifferent in elastic modulus. The organ model is particularly favorableas an organ model for medical procedure trainings, because the organmodel can faithfully reproduce internal structures such as blood vesselsand areas of pathology that are different in hardness and elasticmodulus, can feel very similar to the desired organ when touched or cut,and can be incised with a surgical scalpel.

EXAMPLES

Examples of the present invention will be described below. The presentinvention is not limited to these Examples.

Production Example 1 of Fourth Liquid (Hard Formed Body Liquid)—Production of Hard Formed Body Liquid 1—

A total of 300 g, which included urethane acrylate as a curable material(product name: DIABEAM UK6038 manufactured by Mitsubishi Rayon Co.,Ltd.) (10 parts by mass), neopentyl glycol hydroxy pivalic acid esterdimethacrylate as a curable material (produce name: KAYARAD MANDAmanufactured by Nippon Kayaku Co., Ltd.) (90 parts by mass), aphotopolymerization initiator (product name: IRGACURE 184 manufacturedby BASF GmbH) (3 parts by mass), and a blue pigment as a colorant(product name: LIONOL BLUE 7400G manufactured by Toyo Ink Co., Ltd.) (2parts by mass), was dispersed with a homogenizer (HG30 manufactured byHitachi Koki Co., Ltd.) at a rotation speed of 2,000 rpm until a uniformmixture was obtained. Then, the resultant was filtered to removeimpurities, etc., and finally subjected to vacuum deaeration for 10minutes, to thereby obtain a hard formed body liquid 1.

The surface tension and viscosity of the obtained hard formed bodyliquid 1 were measured in the manners described below. As a result, thesurface tension was 27.1 mN/m, and the viscosity was 10.1 mPa·s at 25°C.

<Surface Tension Measurement>

The surface tension of the obtained hard formed body liquid 1 wasmeasured with a surface tensiometer (an automatic contact angle gaugeDM-701 manufactured by Kyowa Interface Science Co., Ltd.) according to ahanging drop method.

<Viscosity Measurement>

The viscosity of the obtained hard formed body liquid 1 was measuredwith a rotary viscometer (VISCOMATE VM-150III manufactured by TokiSangyo Co., Ltd.) at 25° C.

Example 1 <Production of Three-Dimensional Object Forming Liquid 1(First Liquid or Second Liquid)>

A three-dimensional object forming liquid 1 was produced in the mannerdescribed below based on the composition presented in Table 1.

—Preparation of Water—

Ion-exchanged water deaerated at reduced pressure for 10 minutes wasused as pure water.

—Preparation of Initiator Liquids—

As a photopolymerization initiator liquid, a photopolymerizationinitiator (IRGACURE 184 manufactured by BASF GmbH) (2 parts by mass) wasdissolved in ethanol (98 parts by mass), and prepared as an aqueoussolution.

As a thermal polymerization initiator liquid 1, sodium peroxo disulfate(manufactured by Wako Pure Chemical Industries, Ltd.) (2 parts by mass)was dissolved in pure water (98 parts by mass), and prepared as anaqueous solution.

As a thermal polymerization initiator liquid 2, VA-067 (manufactured byWako Pure Chemical Industries, Ltd.) (2 parts by mass) was dissolved inpure water (98 parts by mass), and prepared as an aqueous solution.

—Preparation of Three-Dimensional Object Forming Liquid 1—

First, while the pure water (195 parts by mass) was stirred, a synthetichectorite (LAPONITE XLG manufactured by Rock Wood Co., Ltd.) having acomposition of [Mg_(5.34)Li_(0.66)Si₈O₂₀(OH)₄]Na⁻ _(0.66) as a layeredmineral (8 parts by mass) was added thereto little by little, and theywere stirred and prepared as a dispersion liquid.

Next, N,N-dimethyl acrylamide (DMAA manufactured by Wako Pure ChemicalIndustries, Ltd.) as a monofunctional monomer (20 parts by mass) whichhad been passed through an active alumina column to remove apolymerization inhibitor, and methylene bis acrylamide (MBAAmanufactured by Wako Pure Chemical Industries, Ltd.) as amultifunctional monomer (0.3 parts by mass) were added to the obtaineddispersion liquid. Further, sodium dodecyl sulfate (manufactured by WakoPure Chemical Industries, Ltd.) as a surfactant (2 parts by mass) wasadded thereto and mixed.

Next, while the resultant was cooled in an ice bath, thephotopolymerization initiator liquid (0.5 parts by mass), and thethermal polymerization initiator liquid 1 (5 parts by mass) were addedthereto. After they were stirred and mixed, the resultant was deaeratedat reduced pressure for 10 minutes. Then, the resultant was filtered toremove impurities, etc., to thereby prepare a three-dimensional objectforming liquid 1.

The surface tension of the obtained three-dimensional object formingliquid 1 measured in the same manner as for the hard formed body liquid1 was 31.3 mN/m, and the viscosity thereof measured in the same manneras for the hard formed body liquid 1 was 9.8 mPa·s at 25° C. Theseresults are presented in Table 1.

<Production of Hydrogel>

Next, the three-dimensional object forming liquid 1 was poured into amold, which was then capped with quartz glass to be airtightly closed.This was irradiated with a light volume of 350 mJ/cm² by an ultravioletray-emitting device (SPOT CURE SP5-250DB manufactured by Ushio Inc.), tothereby produce a hydrogel 1 having a cubic shape having a size of 10mm×10 mm×10 mm.

A compression test of the obtained hydrogel 1 was performed in themanner described below. The result is presented in Table 1.

<Compression Test>

A load cell of 1 kN and a compression jig for 1 kN were set on auniversal tester (AG-I manufactured by Shimadzu Corporation), and thehydrogel 1 having the shape of 10 mm×10 mm×10 mm was placed thereon. Astress corresponding to a compression imposed on the load cell wasrecorded on a computer, and a stress corresponding to an amount ofdisplacement was plotted.

When the hydrogel was broken, the compressive stress when it was brokenwas obtained as a maximum value. When the hydrogel was not broken, themeasurement was obtained as an 80% strain compressive stress.

The compressive elastic modulus of the hydrogel was obtained from themeasurement data acquired by the same universal tester. The compressiveelastic modulus was obtained by calculating a difference between a 10%strain compressive stress and a 20% strain compressive stress, as aslope at a displacement of 10%.

Examples 2 to 8 and Comparative Example 1 <Production ofThree-Dimensional Object Forming Liquids 2 to 9>

Three-dimensional object forming liquids 2 to 9 were prepared in thesame manner as in Example 1, except that the composition and contentswere changed from Example 1 to those presented in Table 1 to Table 3below.

The surface tension and viscosity of the obtained three-dimensionalobject forming liquids 2 to 9 were measured in the same manners as inExample 1. The results are presented in Table 1 to Table 3.

Next, hydrogels 2 to 7 and 9 were produced using the obtainedthree-dimensional object forming liquids 2 to 7 and 9 in the same manneras the production of the hydrogel 1. Further, a hydrogel 8 was producedusing the three-dimensional object forming liquid 8, and with aninfrared ray-emitting device instead of the ultraviolet ray-emittingdevice used in the production of the hydrogel 1.

The compression test of the obtained hydrogels 2 to 9 was performed inthe same manner as for the hydrogel 1. The results are presented inTable 1 to Table 3.

TABLE 1 Ex. Component (part by mass) 1 2 3 4 Three-dimensional objectforming liquid No. 1 2 3 4 Hydrogel No. 1 2 3 4 Layered mineral XLG 8 88 16 Monofunctional monomer 1 DMAA 20 20 — 20 Monofunctional monomer 2IPAM — — 20 — Multifunctional monomer MBAA 0.3 0.15 0.3 0.3 SurfactantNa dodecyl sulfate 2 2 2 2 Photopolymerization IRGACURE 184 0.5 0.5 0.50.5 initiator liquid Thermal polymerization Na peroxo disulfate 5 5 5 5initiator liquid 1 Thermal polymerization VA-067 — — — — initiatorliquid 2 water Pure water 195 195 195 189 Properties of Viscosity (mPa ·s) 9.8 9.8 10.0 18.8 three-dimensional object Surface tension (mN/m)31.1 31.2 31.1 31.1 forming liquid Properties of hydrogel Compressiveelastic modulus 0.20 0.12 0.1 0.4 (MPa) 80% strain compressive stress3.2 1.8 1.2 6.0 (MPa)

TABLE 2 Ex. Component (part by mass) 5 6 7 8 Three-dimensional objectforming liquid No. 5 6 7 8 Hydrogel No. 5 6 7 8 Layered mineral XLG 5 2540 16 Monofunctional monomer 1 DMAA 20 20 20 20 Monofunctional monomer 2IPAM — — — — Multifunctional monomer MBAA 0.6 0.3 0.3 0.3 Surfactant Nadodecyl sulfate 2 2 2 2 Photopolymerization IRGACURE 184 0.5 0.5 0.5 —initiator liquid Thermal polymerization Na peroxo disulfate 5 5 5 —initiator liquid 1 Thermal polymerization VA-067 — — — 10 initiatorliquid 2 water Pure water 195 195 195 195 Properties of Viscosity (mPa ·s) 4.5 38 60 19 three-dimensional object Surface tension (mN/m) 31.231.1 30.1 31.1 forming liquid Properties of hydrogel Compressive elasticmodulus 0.15 0.8 2.0 0.45 (MPa) 80% strain compressive stress 0.8 12 206.3 (MPa)

TABLE 3 Comp. Ex. Component (part by mass) 1 Three-dimensional objectforming liquid No. 9 Hydrogel No. 9 Layered mineral XLG 8 Monofunctionalmonomer 1 DMAA 20 Monofunctional monomer 2 IPAM — Multifunctionalmonomer MBAA — Surfactant Na dodecyl sulfate 2 PhotopolymerizationIRGACURE 184 0.5 initiator liquid Thermal polymerization Na peroxodisulfate 5 initiator liquid 1 Thermal polymerization VA-067 — initiatorliquid 2 water Pure water 195 Properties of Viscosity (mPa · s) 6.5three-dimensional object Surface tension (mN/m) 30.9 forming liquidProperties of hydrogel Compressive elastic modulus 0.1 (MPa) 80% straincompressive stress 0.8 (MPa)

Details of the materials used in Table 1 to Table 3 are as follows.

Layered mineral: XLG: a synthetic hectorite (LAPONITE XLG manufacturedby Rock Wood Co., Ltd.) having a composition of[Mg_(5.34)Li_(0.66)Si₈O₂₀(OH)₄]Na⁻ _(0.66)

Monofunctional monomer 1: DMAA: N,N-dimethyl acrylamide (manufactured byWako Pure Chemical Industries, Ltd.)

Monofunctional monomer 2: IPAM: N-isopropyl acrylamide (manufactured byWako Pure Chemical Industries, Ltd.)

Multifunctional monomer: MBAA: methylene bis acrylamide (manufactured byWako Pure Chemical Industries, Ltd.)

Photopolymerization initiator liquid (IRGACURE 184 (2 parts bymass)/ethanol (98 parts by mass))

Thermal polymerization initiator liquid 1 (Na peroxo disulfate (2 partsby mass)/water (98 parts by mass))

Thermal polymerization initiator liquid 2 (VA-067 (2 parts bymass)/water (98 parts by mass))

Example 9

A three-dimensional object as illustrated in FIG. 4A and FIG. 4B wereproduced using the three-dimensional object forming liquid set presentedin Table 4 and the three-dimensional object forming apparatusillustrated in FIG. 2.

First, the three-dimensional object forming liquid 1 as the first liquidand the three-dimensional object forming liquid 4 as the second liquidwere filled in two tanks leading to inkjet heads (MH2420 manufactured byRicoh Industry Company, Ltd.) of the three-dimensional object formingapparatus. The two kinds of three-dimensional object forming liquidswere jetted from the respective inkjet heads, to thereby form films. Thefirst liquid and the second liquid were jetted to different positions.

Next, the films were irradiated with a light volume of 350 mJ/cm² by anultraviolet ray-emitting device (SPOT CURE SP5-250DB manufactured byUshio Inc.), and thereby cured. These series of steps were repeated, tothereby form a three-dimensional object 1.

The obtained three-dimensional object 1 included a region B made of thehydrogel 4 thereinside, and a region A made of the hydrogel 1 outsidethe region B.

A three-dimensional object structure of the obtained three-dimensionalobject 1 was evaluated as below. The result is presented in Table 5.

<Structure of Three-Dimensional Object>

A: The three-dimensional object was formed of two regions A and Bdifferent in elastic modulus illustrated in FIG. 4A and FIG. 4B. B: Thethree-dimensional object was formed of two regions A and

B different in elastic modulus illustrated in FIG. 4A and FIG. 4B, butwould easily collapse during transportation, and was problematic as athree-dimensional object.

C: The three-dimensional object was not formed of two regions A and Bdifferent in elastic modulus illustrated in FIG. 4A and FIG. 4B.

Example 10

Three-dimensional object formation of a three-dimensional object 2 wasperformed in the same manner as in Example 9, except that unlike inExample 9, the three-dimensional object forming liquid 2 was used as thefirst liquid and the three-dimensional object forming liquid 4 was usedas the second liquid as presented in Table 4. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 11

Three-dimensional object formation of a three-dimensional object 3 wasperformed in the same manner as in Example 9, except that unlike inExample 9, the three-dimensional object forming liquid 3 was used as thefirst liquid and the three-dimensional object forming liquid 4 was usedas the second liquid as presented in Table 4. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 12

Formation of a three-dimensional object 4 and a support member wasperformed using the three-dimensional object forming liquid 1 as thefirst liquid, the three-dimensional object forming liquid 4 as thesecond liquid, and the hard formed body liquid 1 as the fourth liquid aspresented in Table 4 unlike in Example 9. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 13

Three-dimensional object formation of a three-dimensional object 5 wasperformed in the same manner as in Example 9, except that unlike inExample 9, the three-dimensional object forming liquid 5 was used as thefirst liquid and the three-dimensional object forming liquid 4 was usedas the second liquid as presented in Table 4. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 14

Three-dimensional object formation of a three-dimensional object 6 wasperformed in the same manner as in Example 9, except that unlike inExample 9, the three-dimensional object forming liquid 6 was used as thefirst liquid and the three-dimensional object forming liquid 4 was usedas the second liquid as presented in Table 4. The structure of the 2 othree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 15

Three-dimensional object formation of a three-dimensional object 7 wasperformed in the same manner as in Example 9, except that unlike inExample 9, the three-dimensional object forming liquid 7 was used as thefirst liquid and the three-dimensional object forming liquid 4 was usedas the second liquid as presented in Table 4. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 16

Three-dimensional object formation of a three-dimensional object 8 wasperformed using the three-dimensional object forming liquid 1 as thefirst liquid and the three-dimensional object forming liquid 8 as thesecond liquid as presented in Table 4 unlike in Example 9, by repetitionof curing of the three-dimensional object forming liquid 1 byirradiation by an ultraviolet ray-emitting device and curing of thethree-dimensional object forming liquid 8 by heating at 80° C. by aninfrared ray-emitting device as in Example 8. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Example 17

Three-dimensional object formation of a three-dimensional object 9 wasperformed using the three-dimensional object forming liquid 8 as thefirst liquid and the three-dimensional object forming liquid 1 as thesecond liquid as presented in Table 4 unlike in Example 9, by repetitionof curing of the three-dimensional object forming liquid 1 byirradiation by an ultraviolet ray-emitting device and curing of thethree-dimensional object forming liquid 8 by heating at 80° C. by aninfrared ray-emitting device as in Example 8. The structure of thethree-dimensional object was evaluated in the same manner as in Example9. The result is presented in Table 5.

Comparative Example 2

Three-dimensional object formation of a three-dimensional object 10 andformation of a support member were performed in the same manner as inExample 9, except that unlike in Example 9, the three-dimensional objectforming liquid 9 was used as the first liquid, the three-dimensionalobject forming liquid 4 was used as the second liquid, and the hardformed body liquid 1 was used as the fourth liquid as presented in Table4. The structure of the three-dimensional object was evaluated in thesame manner as in Example 9. The result is presented in Table 5.

Comparative Example 3

An internal structure was formed beforehand using a mold and thethree-dimensional object forming liquid 4 as the second liquid. Theinternal structure was set in a mold, the three-dimensional objectforming liquid 1 as the first liquid was poured into the mold, and themold was capped with quartz glass to be airtightly closed They werephoto-cured in the same manner as in Example 9. As a result, the regionB that was to form the central shape could not be fixed at thepredetermined position but fell down, and a three-dimensional objectcould not be produced.

Comparative Example 4

Three-dimensional object formation of a three-dimensional object 11 wasperformed in the same manner as in Example 9, except that unlike inExample 9, only one kind of a three-dimensional object forming liquid,which was the three-dimensional object forming liquid 1, was used aspresented in Table 4. The structure of the three-dimensional object wasevaluated in the same manner as in Example 9. The result is presented inTable 5.

TABLE 4 Three-dimensional object forming liquid set Three-dimensionalobject Hard formed body forming liquid No. liquid No. First liquidSecond liquid Fourth liquid Ex. 9 1 4 — Ex. 10 2 4 — Ex. 11 3 4 — Ex. 121 4 1 Ex. 13 5 4 — Ex. 14 6 4 — Ex. 15 7 4 — Ex. 16 1 8 — Ex. 17 8 1 —Comp. Ex. 2 9 4 1 Comp. Ex. 3 1 (mold) 4 (mold) — Comp. Ex. 4 1 1 —

TABLE 5 Region A of FIGS. 4 Region B of FIGS. 4 80% strain 80% strainStructure of compressive compressive three-dimensional Hydrogel stress(MPa) Hydrogel stress (MPa) object Ex. 9 Hydrogel 1 3.2 Hydrogel 4 6.0 AEx. 10 Hydrogel 2 1.8 Hydrogel 4 6.0 A Ex. 11 Hydrogel 3 1.2 Hydrogel 46.0 A Ex. 12 Hydrogel 1 3.2 Hydrogel 4 6.0 A Ex. 13 Hydrogel 5 0.8Hydrogel 4 6.0 A Ex. 14 Hydrogel 6 12 Hydrogel 4 6.0 A Ex. 15 Hydrogel 720 Hydrogel 4 6.0 A Ex. 16 Hydrogel 1 3.2 Hydrogel 8 6.3 A Ex. 17Hydrogel 8 6.3 Hydrogel 1 3.2 A Comp. Ex. 2 Hydrogel 9 0.8 Hydrogel 46.0 B Comp. Ex. 3 Hydrogel 1 3.2 Hydrogel 4 6.0 Unmeasurable Comp. Ex. 4Hydrogel 1 3.2 Hydrogel 1 3.2 C

Preparation Example 1 <Preparation of First Liquid or Second Liquid(Three-Dimensional Object Forming Liquid) 1-1>

First, while the pure water (195 parts by mass) was stirred, a synthetichectorite (LAPONITE XLG manufactured by Rock Wood Co., Ltd.) having acomposition of [Mg_(5.34)Li_(0.66)Si₈O₂₀(OH)₄]Na⁻ _(0.66) as a layeredmineral (16 parts by mass) was added thereto little by little, and theywere stirred and prepared as a dispersion liquid.

Next, N,N-dimethyl acrylamide (DMAA manufactured by Wako Pure ChemicalIndustries, Ltd.) as a monofunctional monomer (20 parts by mass) whichhad been passed through an active alumina column to remove apolymerization inhibitor, and methylene bis acrylamide (MBAAmanufactured by Wako Pure Chemical Industries, Ltd.) as amultifunctional monomer (0.3 parts by mass) were added to the obtaineddispersion liquid. Further, sodium dodecyl sulfate (manufactured by WakoPure Chemical Industries, Ltd.) as a surfactant (2 parts by mass) wasadded thereto and mixed. After this, the resultant was deaerated atreduced pressure for 10 minutes. Then, the resultant was filtered toremove impurities, etc., to thereby prepare a first liquid or a secondliquid (a three-dimensional object forming liquid) 1-1.

<Storage Stability>

The obtained first liquid or second liquid 1-1 was put in apolypropylene-made wide-mouthed bottle (50 mL) and left in aconstant-temperature bath of 50° C. for two weeks. After this, thebottle was taken out from the constant-temperature bath, left until itbecame room temperature (25° C.), and an initial viscosity (pre-storageviscosity) of the liquid was measured under 1 atm.

The first liquid or second liquid 1-1 was put in a polypropylene-madewide-mouthed bottle (50 mL) and left in a constant-temperature bath of50° C. for two weeks. After this, the bottle was taken out from theconstant-temperature bath. The first liquid or the second liquid 1-1taken out from the constant-temperature bath was left until it becomeroom temperature (25° C.). After this, a post-storage viscosity of theliquid was measured under 1 atm. The pre-storage viscosity and thepost-storage viscosity were measured with a rotary viscometer (VISCOMATEVM-150III manufactured by Toki Sangyo Co., Ltd.).

A viscosity change rate calculated based on the obtained measurementresults according to a mathematical formula 1 below, and storagestability was evaluated based on the criteria described below.

Viscosity change rate (%)=[(post-storage viscosity)−(pre-storageviscosity)]/(pre-storage viscosity)×100  [Mathematical Formula 1]

[Evaluation Criteria]

A: The viscosity change rate was 10% or less.

B: The viscosity change rate was 20% or less but greater than 10%.

C: The viscosity change rate was greater than 20%.

The measurement results of the pre-storage viscosity and post-storageviscosity, and the evaluation results of the storage stability arepresented in Table 6.

Preparation Examples 2 and 4 to 5 <Preparation of First Liquids orSecond Liquids (Three-Dimensional Object Forming Liquids) 1-2, and 1-4to 1-5>

The first liquids or second liquids 1-2, and 1-4 to 1-5 were prepared inthe same manner as in Preparation Example 1, except that the compositionand contents where changed from Preparation Example 1 to those presentedin Table 6.

The storage stability of the obtained first liquids or second liquids1-2, and 1-4 to 1-5 was evaluated in the same manner as in PreparationExample 1. The results are presented in Table 6.

Preparation Example 3 <Preparation of First Liquid or Second Liquid(Three-Dimensional Object Forming Liquid) 1-3>

First, while the pure water (195 parts by mass) was stirred, a synthetichectorite (LAPONITE XLG manufactured by Rock Wood Co., Ltd.) having acomposition of [Mg_(5.34)Li_(0.66)Si₈O₂₀(OH)₄]Na⁻ _(0.66) as a layeredmineral (8 parts by mass) was added thereto little by little, and theywere stirred and prepared as a dispersion liquid.

Next, N-isopropyl acrylamide (IPAM manufactured by Wako Pure ChemicalIndustries, Ltd.) as a monofunctional monomer 2 (20 parts by mass) whichhad been passed through an active alumina column to remove apolymerization inhibitor, and methylene bis acrylamide (MBAAmanufactured by Wako Pure Chemical Industries, Ltd.) as amultifunctional monomer (0.3 parts by mass) were added to the obtaineddispersion liquid. Further, sodium dodecyl sulfate (manufactured by WakoPure Chemical Industries, Ltd.) as a surfactant (2 parts by mass) wasadded thereto and mixed.

Next, while the resultant was cooled in an ice bath, thephotopolymerization initiator liquid (1 part by mass), and the thermalpolymerization initiator liquid 1 (10 parts by mass) were added thereto.After they were stirred and mixed, the resultant was deaerated atreduced pressure for 10 minutes. Then, the resultant was filtered toremove impurities, etc., to thereby prepare a first liquid or a secondliquid (a three-dimensional object forming liquid) 1-3.

The storage stability of the obtained first liquid or second liquid 1-3was evaluated in the same manner as in Preparation Example 1. The resultis presented in Table 6.

Preparation Examples 6 to 8 <Preparation of Third Liquids 3-1 to 3-3>

Third liquids 3-1 to 3-3 were prepared in the same manner as inPreparation Example 3, except that the composition and contents werechanged from Preparation Example 3 to those presented in Table 7 below.

The storage stability of the obtained third liquids 3-1 to 3-3 wasevaluated in the same manner as in Preparation Example 1. The resultsare presented in Table 7.

TABLE 6 Three-dimensional object forming liquid First liquid or secondliquid No. Component (part by mass) 1-1 1-2 1-3 1-4 1-5 MultifunctionalMBAA 0.3 0.15 0.3 0.3 — monomer Layered mineral XLG 16 8 8 — 8Photopolymerization IRGACURE — — 1 — — initiator liquid 184 Thermal Naperoxo — — 10 — — polymerization disulfate initiator liquid 1Monofunctional DMAA 20 — — 20 20 monomer 1 Monofunctional IPAM — 20 20 —— monomer 2 Surfactant Na dodecyl 2 2 2 2 2 sulfate water Pure water 195195 195 195 195 Storage stability Initial 12.4 8.8 13.3 4.5 5.8viscosity (mPa · s) Storage 13.7 9.5 16.6 4.9 6.1 viscosity (mPa · s)Evaluation B A C A A

TABLE 7 Third liquid No. Component (part by mass) 3-1 3-2 3-3Multifunctional MBAA — 0.3 — monomer Layered mineral XLG — — —Photopolymerization IEGACURE 184 1.5 1 1.5 initiator liquid Thermal Naperoxo disulfate 15 10 15 polymerization initiator liquid 1Monofunctional DMAA — 20 — monomer 1 Monofunctional IPAM — — 20 monomer2 Surfactant Na dodecyl sulfate 2 2 2 water Pure water 195 195 195Storage stability Initial viscosity 7.2 9.2 9.9 (mPa · s) Storageviscosity 7.7 10.3 10.6 (mPa · s) Evaluation A B A

Details of the materials used in Table 6 and Table 7 are as follows.

Layered mineral: XLG: a synthetic hectorite (LAPONITE XLG manufacturedby Rock Wood Co., Ltd.) having a composition of[Mg_(5.34)Li_(0.66)Si₈O₂₀(OH)₄]Na⁻ _(0.66)

Monofunctional monomer 1: DMAA: N,N-dimethyl acrylamide (manufactured byWako Pure Chemical Industries, Ltd.)

Monofunctional monomer 2: IPAM: N-isopropyl acrylamide (manufactured byWako Pure Chemical Industries, Ltd.)

Multifunctional monomer: MBAA: methylene bis acrylamide (manufactured byWako Pure Chemical Industries, Ltd.)

Photopolymerization initiator liquid (IRGACURE 184 (2 parts bymass)/ethanol (98 parts by mass))

Thermal polymerization initiator liquid 1 (Na peroxo disulfate (2 partsby mass)/water (98 parts by mass))

Examples 18 to 20 and 22

Three-dimensional objects were produced using the three-dimensionalobject forming liquid sets presented in Table 8 and thethree-dimensional object forming apparatus illustrated in FIG. 2.

Specifically, first, the first liquid or the second liquid, and thesecond liquid presented in Table 8 were filled in two tanks leading toinkjet heads (MH2420 manufactured by Ricoh Industry Company, Ltd.) ofthe three-dimensional object forming apparatus. The two kinds of liquidswere jetted from the respective inkjet heads, to thereby form films. Thethird liquid was jetted to the same position to which the first liquidor the second liquid was jetted.

Next, the films were irradiated with ultraviolet rays having a lightvolume presented in Table 8 by an ultraviolet ray-emitting device (SPOTCURE SP5-250DB manufactured by Ushio Inc.), and thereby cured. Theseseries of steps were repeated, to thereby form three-dimensional objectsof Examples 18 to 20 and 22.

Example 21

A three-dimensional object of Example 21 was produced in the same manneras in Examples 18 to 20 and 22, except that as presented in Table 8, thehard formed body liquid 1 was used in the support member-jetting headunit 31 illustrated in FIG. 2 as the three-dimensional object formingliquid set to form the three-dimensional object and a support member.

Next, an 80% strain compressive stress of the obtained three-dimensionalobjects of Examples 18 to 22 was measured in the manner described below.The results are presented in Table 8.

<80% Strain Compressive Stress Evaluation (Compression Test)>

A load cell of 1 kN and a compression jig for 1 kN were set on auniversal tester (AG-I manufactured by Shimadzu Corporation), and thethree-dimensional object having a shape of 10 mm×10 mm×10 mm was placedthereon. A stress corresponding to a compression imposed on the loadcell was recorded on a computer, and a stress corresponding to an amountof displacement was plotted.

When the three-dimensional object was broken, the compressive stresswhen it was broken was obtained as a maximum value. When thethree-dimensional object was not broken, the measurement was obtained asan 80% strain compressive stress. The values were evaluated based on thecriteria below.

[Evaluation Criteria]

A: The 80% strain compressive stress of the three-dimensional object was1.0 MPa or greater.

B: The 80% strain compressive stress of the three-dimensional object was0.4 MPa or greater but less than 1.0 MPa.

C: The 80% strain compressive stress of the three-dimensional object wasless than 0.4 MPa.

TABLE 8 Ex. 18 Ex. 19 Ex. 20 Ex. 21 Ex. 22 Three-dimensional Firstliquid No. 1-1 1-1 1-2 1-1 1-1 object forming Second liquid No. — — — —— liquid set Third liquid No. 3-1 3-2 3-3 3-1 3-1 Fourth liquid No. — —— 1 — Light volume mJ/cm² 350 350 350 350 280 during curing 80% strainMeasured value (MPa) 3.4 2.5 2.8 3.4 3.0 compressive stress Evaluation AA A A A

Example 23

An organ model of a porcine liver was formed using the three-dimensionalobject forming liquid 1, the three-dimensional object forming liquid 4,and the hard formed body liquid 1 as in the three-dimensional objectforming liquid set of Example 12, and with the three-dimensional objectforming apparatus illustrated in FIG. 2, based on three-dimensionalmodel data of the liver obtained by performing data processing accordingto the description in JP-B No. 5239037.

The obtained liver organ model had similar shape, touch, and elasticityto those of a real porcine liver.

Aspects of the present invention are as follows, for example.

<1> A three-dimensional object producing method, including:

a first step of forming a film by delivering a first liquid as ahydrogel precursor including at least a multifunctional monomer; and

a second step of curing the film formed in the first step,

wherein the first step and the second step are repeated a plurality oftimes.

<2> A three-dimensional object producing method, including:

a first step of forming a film by delivering a first liquid as ahydrogel precursor including at least a multifunctional monomer;

a third step of forming a film by delivering a second liquid including ahydrogel precursor and compositionally different from the first liquidto a different position from where the first liquid is delivered; and

a fourth step of curing the films formed in the first step and the thirdstep respectively,

wherein the first step, the third step, and the fourth step are repeateda plurality of times.

<3> The three-dimensional object producing method according to <1>,further including:

a fifth step of delivering a third liquid including at least apolymerization initiator to the same position as where the first liquidis delivered.

<4> The three-dimensional object producing method according to <2>,further including:

a sixth step of delivering a third liquid including at least apolymerization initiator to the same position as at least any one ofwhere the first liquid is delivered and where the second liquid isdelivered.

<5> The three-dimensional object producing method according to <4>,

wherein a content of the polymerization initiator in the third liquid isgreater than a content of a polymerization initiator in at least any oneof the first liquid and the second liquid.

<6> The three-dimensional object producing method according to any oneof <2>, <4>, and <5>,

wherein at least any one of the first liquid and the second liquid isfree of a polymerization initiator.

<7> The three-dimensional object producing method according to any oneof <2> and <4> to <6>,

wherein at least any one of the first liquid and the second liquidincludes a polymerization initiator.

<8> The three-dimensional object producing method according to any oneof <3> to <5> and <7>,

wherein the polymerization initiator is any one of a photopolymerizationinitiator and a thermal polymerization initiator.

<9> The three-dimensional object producing method according to any oneof <1> to <8>,

wherein the hydrogel precursor includes at least a layered mineraldispersed in water in a state of single layers.

<10> The three-dimensional object producing method according to any oneof <2> and <4> to <9>,

wherein at least any one of the first liquid and the second liquidincludes a monofunctional monomer.

<11> The three-dimensional object producing method according to any oneof <2> and <4> to <10>,

wherein the second liquid includes a multifunctional monomer.

<12> The three-dimensional object producing method according to any oneof <9> to <11>,

wherein the layered mineral is a synthetic hectorite.

<13> The three-dimensional object producing method according to any oneof <1> to <12>,

wherein the multifunctional monomer is an active energy ray-curablemonomer.

<14> The three-dimensional object producing method according to any oneof <10> to <13>,

wherein a homopolymer of the monofunctional monomer or themultifunctional monomer is water-soluble.

<15> The three-dimensional object producing method according to <1> or<2>,

wherein a method for delivering the first liquid is any one of an inkjetmethod and a dispenser method.

<16> The three-dimensional object producing method according to <2>,

wherein a method for delivering the second liquid is any one of aninkjet method and a dispenser method.

<17> The three-dimensional object producing method according to <3> or<4>,

wherein a method for delivering the third liquid is any one of an inkjetmethod and a dispenser method.

<18> A three-dimensional object producing method, including:

a first step of forming a film by delivering a first liquid;

a third step of forming a film by delivering a second liquid to adifferent position from where the first liquid is delivered; and

a fourth step of curing the films formed in the first step and the thirdstep respectively,

wherein the first step, the third step, and the fourth step are repeateda plurality of times, and

wherein the first liquid and the second liquid are cured to hydrogelsdifferent from each other in elastic modulus.

<19> The three-dimensional object producing method according to <18>,further including:

a sixth step of delivering a third liquid including at least apolymerization initiator to the same position as at least any one ofwhere the first liquid is delivered and where the second liquid isdelivered.

<20> The three-dimensional object producing method according to <18> or<19>,

wherein an 80% strain compressive stress of one of the hydrogels is 0.4MPa or greater.

<21> The three-dimensional object producing method according to any oneof <18> to <20>, further including:

a seventh step of forming a film by delivering a fourth liquid to becomea hard formed body for supporting a three-dimensional object made of thehydrogels to a different position from at least any one of where thefirst liquid is delivered and where the second liquid is delivered.

<22> A three-dimensional object forming liquid,

wherein the three-dimensional object forming liquid is a hydrogelprecursor including at least a multifunctional monomer.

<23> The three-dimensional object forming liquid according to <22>,

wherein a viscosity of the three-dimensional object forming liquid isfrom 3 mPa·s to 20 mPa·s at 25° C., and an 80% strain compressive stressof a hydrogel obtained by curing the three-dimensional object formingliquid is 0.4 MPa or greater.

<24> A three-dimensional object forming liquid set, including:

a first liquid as a hydrogel precursor including at least amultifunctional monomer; and

a second liquid including a hydrogel precursor and compositionallydifferent from the first liquid.

<25> The three-dimensional object forming liquid set according to <24>,further including:

a third liquid greater than at least any one of the first liquid and thesecond liquid in a content of a polymerization initiator.

<26> The three-dimensional object forming liquid set according to <25>,

wherein a viscosity change rate of the third liquid before and after thethird liquid is left at 50° C. for two weeks is 20% or less.

<27> The three-dimensional object forming liquid set according to anyone of <24> to <26>,

wherein at least any one of the first liquid and the second liquid isfree of a polymerization initiator.

<28> The three-dimensional object forming liquid set according to anyone of <24> to <26>,

wherein at least any one of the first liquid and the second liquidincludes a polymerization initiator.

<29> The three-dimensional object forming liquid set according to anyone of <26> to <28>,

wherein the polymerization initiator is any one of a photopolymerizationinitiator and a thermal polymerization initiator.

<30> The three-dimensional object forming liquid set according to anyone of <24> to <29>,

wherein the first liquid and the second liquid are cured to hydrogelsdifferent from each other in elastic modulus.

<31> A three-dimensional object, including at least:

a first region made of a first hydrogel; and

a second region made of a second hydrogel different from the firsthydrogel in elastic modulus,

wherein an 80% strain compressive stress of any one of the firsthydrogel and the second hydrogel is 0.4 MPa or greater.

<32> The three-dimensional object according to <31>,

wherein compressive elastic modulus of any one of the first hydrogel andthe second hydrogel is 0.3 MPa or greater.

<33> The three-dimensional object according to <31> or <32>,

wherein the first region encloses the second region therein completely.

<34> The three-dimensional object according to any one of <31> to <33>,

wherein the hydrogels are hydrogels including water in athree-dimensional network structure formed by a water-soluble organicpolymer and dispersed single layers of a layered mineral being combinedwith each other.

<35> The three-dimensional object according to any one of <31> to <34>,

wherein the three-dimensional object is used as an organ model.

The three-dimensional object producing method according to any one of<1> to <21>, the three-dimensional object forming liquid according to<22> or <23>, the three-dimensional object forming liquid set accordingto any one of <24> to <30>, and the three-dimensional object accordingto any one of <31> to <35> aim to solve the various conventionalproblems described above and achieve the object described below. Thatis, the three-dimensional object producing method, the three-dimensionalobject forming liquid, the three-dimensional object forming liquid set,and the three-dimensional object aim to provide a three-dimensionalobject producing method, a three-dimensional object forming liquid, athree-dimensional object forming liquid set, and the three-dimensionalobject that enable easily and efficient production of complicated finethree-dimensional objects represented by organ models, etc.

This application claims priority to Japanese application No.2014-211658, filed on Oct. 16, 2014 and incorporated herein byreference, and Japanese application No. 2015-120796, filed on Jun. 16,2015 and incorporated herein by reference.

1.-13. (canceled)
 14. A three-dimensional object forming liquid, whereinthe three-dimensional object forming liquid is a hydrogel precursor thatcomprises a multifunctional monomer, and wherein a viscosity of thethree-dimensional object forming liquid is from 3 mPa·s to 20 mPa·s at25° C., and an 80% strain compressive stress of a hydrogel obtained bycuring the three-dimensional object forming liquid is 0.4 MPa orgreater.
 15. A three-dimensional object forming liquid set, comprising:a first liquid that is the three-dimensional object forming liquidaccording to claim 14; and a second liquid that comprises a hydrogelprecursor and is compositionally different from the three-dimensionalobject forming liquid.
 16. A three-dimensional object produced by athree-dimensional object producing method comprising: forming of a filmby delivering a first liquid; another forming of a film by delivering asecond liquid to a different position from where the first liquid isdelivered; and curing of the films formed in the forming and the anotherforming respectively, wherein the forming, the another forming, and thecuring are repeated a plurality of times, and wherein the first liquidand the second liquid are cured to hydrogels different from each otherin elastic modulus, the three-dimensional object comprising: a firstregion made of a first hydrogel; and a second region made of a secondhydrogel different from the first hydrogel in elastic modulus, whereinan 80% strain compressive stress of any one of the first hydrogel andthe second hydrogel is 0.4 MPa or greater.
 17. The three-dimensionalobject according to claim 16, wherein compressive elastic modulus of anyone of the first hydrogel and the second hydrogel is 0.3 MPa or greater.18. The three-dimensional object according to claim 16, wherein thefirst region encloses the second region therein completely.
 19. Thethree-dimensional object according to claim 16, wherein the hydrogelsare hydrogels that comprise water in a three-dimensional networkstructure formed by a water-soluble organic polymer and dispersed singlelayers of a layered mineral being combined with each other.
 20. An organmodel, wherein the organ model is the three-dimensional object accordingto claim 16.